| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide slaves capable of notifying a state such as abnormality of equipment to be controlled (to be monitored) while suppressing the load of a programmable controller (PLC) etc. <P>SOLUTION: A master unit 2 constituting the PLC1 and a plurality of slaves 10 are connected with a field network 3. Four temperature sensors 5 are connected with the slaves, the temperature sensors measure temperatures of different control targets 6, respectively and transmits them to the slaves. A plurality of control targets are the same kind and any one shows the same heating state when they are in normal states. The slaves arithmetically operate fetched temperature data inside, calculate difference between temperatures (analog data) detected by the plurality of connected temperature sensors, compare the difference with a threshold and notifies the PLC of only its result. Namely, since each temperature is approximately equal when the control targets are normal, the difference becomes equal to or less than the threshold, however, when a certain control target breaks down, only temperature of the control target rises and the difference exceeds the threshold. Thus, the abnormality is detected. The slaves perform to abnormality decision and notifies its result. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
